Ion flux kinetics in blue light-grown field dodder (Cuscuta campestris) seedlings

Abstract

Previous studies have revealed that blue light stimulates coiling and prehaustoria development in young de-etiolated dodder seedlings prior to host attachment. In this study, the Ca2+ and H+ flux kinetics that are associated with blue light-mediated coiling and prehaustoria development in de-etiolated dodder seedlings were measured uninvasively using the ion-selective, vibrating microelectrode ion flux system. The findings showed that blue light induces rapid transient changes in the net Ca2+ and H+ fluxes. A clearly pronounced lag of about several minutes was observed between the blue light-induced changes in the Ca2+ and H+ fluxes, with H+ being a leading ion. The addition of 1molL-1 vanadate, a known blocker of the plasma-membrane H+-ATPase, to the bathing solution completely prevented both the H+ and the Ca2+ flux responses and inhibited coiling and prehaustoria development, suggesting a causal relationship between the blue light-induced changes in the net Ca2+ and H+ fluxes and seedling movements. It is concluded that the plasma-membrane H+-ATPase plays a key role in a dodder's parasitic mode of growth and its adaptive response to the environment. © 2015 Weed Science Society of Japan.